"More precisely the states must be formed of two up quarks, one down quark, one charm quark and one anti-charm quark.”
I could get prison time for opening mail that is addressed to only my wife.
No you couldn't. Well, I'm assuming you live with your wife and didn't steal the letter from her mailbox. The relevant law is 18 USC S 1702 "Obstruction of correspondence"
Whoever takes any letter, postal card, or package out of any post office or any authorized depository for mail matter, or from any letter or mail carrier, or which has been in any post office or authorized depository, or in the custody of any letter or mail carrier, before it has been delivered to the person to whom it was directed, with design to obstruct the correspondence, or to pry into the business or secrets of another, or opens, secretes, embezzles, or destroys the same, shall be fined under this title or imprisoned not more than five years, or both.
Notice that it includes taking, opening, and destroying, all equally. If it was a felony to open your wife's mail, it would be an equal felony to remove it from the mailbox and bring it inside. It's not a felony. Mostly because this only applies while the mail is in the possession of the post office. Contrary to a related urban legend, your mailbox is not considered property of the post office. Once the letter is placed there, it is considered delievered. Taking mail from somebody else's mailbox is considered "theft" which is not a federal crime. Some states make mail theft worse than regular theft, but it's stealing regardless.
Because the law is "delievered to the person to whom it was directed" it is may still be considered "obstruction of correspondence" if you open or destroy somebody else's mail, if it was delievered to you accidentially. However, the key is still that your intent was to prevent them from getting the mail, or to pry into their secrets. If you get a letter, open it, and realize "hey, who is this from?" you are not a felon. You still need to get it back to the post office so they can deliver it properly (if they put it in the wrong box) or return it to the sender (if the person has moved without a forwarding address), otherwise you are obstructing the deliever (this is the "secreting" part of the law). But again, the law requires intent. It's not a crime if you just forget to do it.
Every successful person has had failures but repeated failure is no guarantee of eventual success.